Woven fabric is used for versatile purposes. In some cases, a fabric is required to be stretchable beyond its original stretchability. Many methods have been introduced to produce a fabric that is available for those purposes. Among those conventional methods the most practical method requires that a fabric constructed with an orthogonal warp and weft structure be cut diagonally across the width to obtain a biased fabric. However, this method has the disadvantages that the fabric pieces diagonally cut are not sufficiently long enough or use thereby requiring that many pieces be pieced together to make a long biased fabric and that the selvages where warp density is high need to be removed to obtain a uniform property throughout the pieced bias fabric. Furthermore, an inevitable is disadvantage is that although the fabric is cut on the bias, the stretchability is limited within a narrow range In other methods, the weft is inserted diagonally across the width of fabric on a special loom or a hollow woven tubular fabric is cut open in a spiral and extended to deform the intersecting angle of warp and weft. However, those methods require special looms or devices and there is some inconvenience in applying them to practical production.
The advantage of the apparatus according to the invention is that a running length of fabric is efficiently and continuously converted into a bias fabric.
Another advantage of the invention is that a bias fabric produced by the apparatus according to the invention is provided with a feature that physical properties in each orthogonal direction are quite different from each other which is often important when the bias fabric is used as industrial material.